Post on 31-Jul-2019
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FORMULATION OF MELAMINE UREA FORMALDEHYDE (MUF) RESIN BY
USING VARIOUS TYPES OF FILLER
NORLIZA BINTI ISHAK
Thesis submitted in fulfillment of the requirement
for the award of the degree of Bachelor in Chemical Engineering
Faculty of Chemical and Natural Resources Engineering
UNIVERSITI MALAYSIA PAHANG
JANUARY 2012
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ABSTRACT
The performance of adhesive in term of working properties and quality is
improved by the types of material use as filler. Industrial Flour (IF), Pre treatment and post
treatment Palm Kernel Meal (PKM) and Palm Kernel Cake (PKC) are chosen for this
research as filler for the comparison in wood adhesive production. Melamine Urea
Formaldehyde (MUF) resin is selected as the resin for wood adhesive production because
of less costly and high water resistant compared to Melamine Formaldehyde (MF) and Urea
Formaldehyde (UF) resins (Dunky, 2003). This is because the cost of MUF resins depends
on the ratio of melamine and urea. The objective is to compare the types of filler use for
wood adhesive production in term of working properties and its quality. The shear strength
and wood failure for wood adhesive was studied to determine the working properties of
plywood. The experiments were conducted with temperature in specific range and the
pressing time from 50s to 350s. The sieve shaker experiment will be done by using
different type of sieve to get the different sizes of filer’s particle size, to use the uniform
size of fillers. The research study can be conclude that the better performance of wood
adhesive in term of mechanical properties likes strength, durability and quality are based on
materials which is types of filler use whether using Industrial Flour (IF), pre treatment and
post treatment Palm Kernel Meal (PKM) or Palm Kernel Cake (PKC). The optimum value
of temperature and pressing time were determined using Response Surface Methodology
(RSM).
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ABSTRAK
Prestasi pelekat dari segi sifat kerja dan kualiti dapat dipertingkat oleh jenis
penggunaan bahan sebagai pengisi. Tepung gandum, Palm kernel yang belum dirawat dan
yang telah dirawat iaitu palm kernel meal dan palm kernel cake telah dipilih sebagai pengisi
dalam penghasilan pelekat kayu untuk kajian ini. Resin Melamin Urea Formaldehid (MUF)
dipilih sebagai resin untuk penghasilan pelekat kayu kerana kos yang rendah dan kalis air
berbanding dengan resin Melamin Formaldehid (MF) dan Urea Formaldehid (UF) (Dunky
2003). Hal ini kerana kos resin MUF bergantung kepada nisbah melamin dan urea. Objektif
kajian ini adalah untuk membandingkan jenis penggunaan pengisi untuk penghasilan
pelekat kayu berdasarkan sifat kerja dan juga kualiti. Kekuatan ricih dan kekuhan kayu
untuk pelekat kayu dikaji untuk menentukan sifat-sifat kekuatan papan lapis. Eksperimen
ini telah dijalankan dengan suhu dalam julat tertentu dan masa menekan dari 50 saat
sehingga 350 saat. Pengisi diayak dengan menggunakan saiz ayak yang berbeza untuk
mendapatkan saiz zarah yang berlainan untuk dijadikan sebagai saiz pengisi yang seragam.
Oleh itu, kajian penyelidikan ini boleh dikonklusikan bahawa prestasi pelekat kayu yang
baik adalah berdasarkan sifat-sifat mekanikal seperti kekuatan, ketahanan dan kualiti yang
mana bergantung kepada jenis penggunaan pegisi sama ada menggunakan tepung gandum,
Palm kernel yang belum dirawat dan yang telah dirawat iaitu palm kernel meal dan palm
kernel kek. Nilai optimum untuk suhu dan masa menekan ditentukan dengan menggunakan
kaedah tindakbalas permukaan.
CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION
Malaysia is one of the wood suppliers of wood-based products in world region,
especially to Japan, Taiwan, Singapore and Middle East. According by Malaysia Timber
Industry Board, Malaysia is the leader for the production and export of veneer, tropical log
wood and plywood. Total plywood exports from Malaysia amounted to RM 5000 million in
2009 and RM 4900 million in 2010 (Malaysian Timber Industries Board, 2010).
Adhesive is the material that applied to the surfaces of particles to join them
permanently by and adhesive bonding (Wu.s, 1982). According to Hartland S (2004),
adhesion is about two different bodies were held together by intimate interfacial contact
such that mechanical force or work can be transfer across the interface.
There are several types of thermosetting adhesives such as Melamine Formaldehyde
(MF), Urea Formaldehyde (UF) and Melamine Urea Formaldehyde (MUF). For this
research, the thermosetting adhesive used is MUF. Melamine urea formaldehyde (MUF)
resin is a thermosetting polymer type which is produced by the reaction between urea with
melamine and formaldehyde (Pizzi.A, 1994). According to Rowell (2005), MUF used for
this research because less costly depends on melamine and urea ratio and have better water
resistant compared to UF and MF.
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This research is to find out the performance of MUF resin based adhesives by using
various types of filler in terms to compare the mechanical properties of the materials. The
filler in the adhesive is used to fill up all small holes at the surface of wood to prevent or to
reduce the formation of weaker boding. Besides that, fillers also used to reduce the
penetration of resin into the small holes of the wood (Pizzi, 1994). The filler that are using
for this study are post treatment and pre treatment palm kernel which are Palm Kernel Meal
(PKM) and Palm Kernel Cake (PKC) and also Industrial Flour (IF). PKM is the by product
palm kernel oil industry by using extraction method from the meat in the nut of the palm oil
fruit (Bono.A, 2009). The extraction method is actually the treatment to remove the oil in
order to increase the protein level. According to Ong et.al (2004), PKC is a tropical agro-
industrial by-product which is obtained from the palm oil industry which is already been
used in the production of a variety of microbial enzymes such as alpha amylase,
metalloprotease, tannase and mannanase.
Thus, this study will also to find out the performance of MUF resins with various
filler as a wood adhesive based on several factors by using the several method of testing.
1.2 RESEARCH BACKGROUND
Production of wood adhesive for wood industries are the approaches for establishes
the safety wood products for the world in future. A MUF resins with Palm Kernel Meal
(PKM) is contributes to reduces the non environmental issues. Current research developed
by a research team of the Department of Chemical Engineering in University Malaysia
Sabah, (UMS) was studied the MUF resin as based wood adhesive in Malaysia. It states
that the MUF resin properties are affected by the all components; melamine, formalin,
urea1, urea2 and Ammonium Chloride (NH3Cl) as a hardener. The filler using which is
PKM, PKC and IF is an amides groups because of the protein present in this fillers.
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1.3 PROBLEM STATEMENTS
Filler are the important thing for MUF resin based adhesive to enhance binder
performance for produce the good plywood adhesive (Sellers et.al, 2005). Based on
Economic term, the industrial flour is too expensive and also has lower wood performance.
Therefore this study is to investigate the performance of formulation of melamine urea
formaldehyde (MUF) resin as a based adhesive according to the material which is the
filler’s types, pressing time and temperature.
1.4 RESEARCH OBJECTIVES
Based on the aforementioned research background and problem statement, the
objectives of this study are:
I. To compare the types of filler using such as Palm Kernel Meal (PKM), Palm Kernel
Cake (PKC) and Industrial Flour (IF) in MUF resins as a based adhesive
production.
II. To investigate the performance of MUF resins with various filler as a wood
adhesive based on several factors by using the several method of testing.
1.5 RESEARCH SCOPES
In order to accomplish the objectives, the scope of this research is focusing on the
several criteria. Basically, this research is to study the performance melamine urea
formaldehyde (MUF) by using various types of filler. Therefore, the scope of this study is
preparation of fillers such as palm kernel meal (PKM), palm Kernel Cake (PKC) and
industrial flour (IF) filler with MUF resin in uniform particle size of filler. However, this
research also carried out with shear strength test and wood failure for adhesive product in
order to investigate it performance according to Japanese Agriculture Standard (JAS)
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(Japanese Agriculture Standard, 2003). Software Design Expert which is Research Surface
Methodology (RSM) will be applied for result analysis.
1.6 RATIONAL AND SIGNIFICANCE
MUF resins is wood adhesive for wood industries are the approaches for establishes
the safety wood products for the world in future. “MUF resin is safer than Melamine
Formaldehyde (MF) and Urea formaldehyde (UF) because the combination of melamine
and urea will reduces the formalin that can cause carcinogenic in the resins”.
The filler use in industries is high costly. The filler uses in industries have the high
cost but low working performance. Therefore, this study was done because the low cost
material but high working performance as fillers in wood based adhesive is still in research.
Since the Palm Kernel Meal (PKM) and Palm Kernel Cake (PKC) are green product
and non toxic can be used as filler in formulation of MUF resins.
CHAPTER 2
LITERATURE REVIEW
2.1 PLYWOOD
Plywood is a wood product manufactured out of many sheets of veneer, or plies,
pressed together and glued, with their grains going in opposite directions. It might be
extremely strong, though not very attractive, and was treated in many different ways
depend on its application (Smith et.al, 2003). The other definition of plywood is a laminate
made of thin layers of wood.
According to Rowell et.al (2005), plywood is the thin veneer wood layers bonded
together by an adhesive into sheet form. There are two types of plywood which is
construction plywood and decoration plywood. The construction plywood was produced
using softwoods while the decoration plywood was produced using softwoods and also
with hardwoods layer in outer surface.
Plywood structures or also known as ordered fibrous composites are frequently
encountered in natural systems, mostly in skeletal or protective extracellular tissues where
mineral deposition often occurs (Guille MM et.al., 1998).
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2.2 RESIN
Resin is any class of solid, semi solid or liquid organic material generally the
product of natural or synthetic origin with a high molecular weight and with no melting
point (Harper et.al, 1996). The primary functions of the resin are to transfer stress between
the reinforcing fibers, act as a glue to hold the fibers together, and protect the fibers from
mechanical and environmental damage (American Composites Manufactures Association,
2004).
In addition, resin is a natural or synthetic compound which begins in a highly
viscous state and hardens with treatment. Typically, resin is soluble in alcohol, but not in
water. There are a number of different classes of resin, depending on exact chemical
composition and potential uses. There are numerous applications for resins, ranging from
art to polymer production, and many consumers interact with products which contain resin
on a daily basis. Natural resin comes from plants while synthetic resins made by adding
polymer and resins which is cheaper and easier to refine. Basically, synthetic resin is much
more stable, predictable, and uniform than natural resin as well, since it is made under
controlled conditions without the possibility of the introduction of impurities. These resins
are made by combining chemicals in a laboratory to stimulate a reaction which results in
the formulation of a resinous compound (WiseGEEK, 2003).
The synthetic resins consist of two types which is thermosetting and thermoplastic
that used in the production of plastics, paints, and many of the same substances that natural
resin was used in.
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2.3 THERMOSETTING RESINS
Thermosetting resins are usually liquids or low melting point solids in their initial
form. When used to produce finished goods, these thermosetting resins are preserved by the
use of a catalyst, heat or a combination of the two. Once cured, the solid thermosetting
resins cannot be converted back to their original liquid form (American Composites
Manufactures Association, 2004).
Figure 2.1: Estimation of World Thermosetting Resin Production
The figure above shows the market share estimation market share of world
thermosetting resin production by material in 2002. The thermosetting resins consume
totaling virtually 25% of the world’s total plastics production. Based on the data,
Polyurethanes (PU) at 34% comprise the major sector of that current consumption, with
urea-formaldehyde (UF) at 32%, phenol-formaldehyde (PF) at 15%, unsaturated polyesters
(UP) at 9%, epoxies at 5%, melamine-formaldehyde (MF) at 4% and 1% is for others
taking up the remainder. These percentage breakdowns are not expected to change
significantly by 2007, although some resins, for example the epoxies, are expected to see
growth in excess of the forecast 2.5% over the next five years at the expense of other
thermosetting resin. The current worldwide consumption of thermosetting resins across the
epoxy
5%
MF
4% others
1%
UP
9%
PF
15%
UF
32%
PU
34%
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whole industrial is totally in 27 million tones. Collectively, that industry continues to grow
a rate forecast to marginally over 2.5% per annum. Taking that estimate, some five years
from now the consumption will have risen to 31 million tones (Forsdyke et.al, 2002).
The most common thermosetting resins used in the composites industry are
unsaturated polyesters, epoxies, vinyl esters and phenolics. The difference between these
groups the proper material for a specific application.
2.4 MELAMINE UREA FORMALDEHYDE (MUF) RESIN
Melamine urea formaldehyde resin (MUF) is an adhesive thermosetting resin.
According to Pizzi.A et.al (1994), Melamine urea formaldehyde (MUF) resin is a
thermosetting polymer type which is produced by the reaction between urea with melamine
and formaldehyde. Based on the research done by Bono et.al (2003), the MUF resin is
affected by the dosage of mole ratio of Melamine and Formaldehyde and also the molar
ratio of the Urea at each reaction stage in which the amino compounds are reacted.
However, the containing of Melamine in this resin will increase the bonding strength and
reduced the formaldehyde emission compared to the others adhesive thermosetting resins
such as Melamine Formaldehyde (MF) and Urea Formaldehyde (UF) resins (Northeast
Forestry University, 2009).
Figure 2.2: molecular structure for Melamine-Urea-Formaldehyde
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Nowadays, the MUF resins are widely used as an adhesive in wood production,
coating technologies, paper industries and also as a main material in kitchenware
production. In different application, many types of MUF resins properties are needed.
Table 2.1: Design Layout of MUF resin (A.Bono et.al, 2003)
Types of MUF Formulation F1 F2 F3 F4
Number of reaction stage 3 2 3 3
In 1st and 2
nd Stage of Resin Processing
F: U1
F:M1
F: (U1+M1)
(Total mole ratio)
8.00
3.00
2.20
3.38
3.03
1.6
8.50
2.97
2.20
9.00
2.91
2.20
In 3rd
Stage of Resin Processing
F:U3
F: (U+M)
(total/final mole ratio)
Mel% (of total resin weight)
Urea% (of total resin weight)
3.38
1.60
29.56
12.67
-
1.60
29.56
12.65
3.47
1.60
30.16
12.27
3.55
1.60
30.62
11.97
Table above was regarding the design experiment in observation of reaction in
formulation of Melamine Urea Formaldehyde resin. The resin was produced at different
number of reaction stages and different mole ratio for each reaction stages in order to
determine the resin curing period, solubility in water and resin storage stability.
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2.5 FILLER
Nowadays filler is the most important thing as part of based wood adhesive to
improve the working material in order to produce the good wood adhesive. Ebnessajad
(2008) stated that the term filler refer to the neutral substances that was added to the
adhesive to improve the workings properties of that material in term of strength,
permanence and also quality. According by (Bosshard et.al, 1996) filler was refers to solid
additives that are incorporated into the plastic matrix and can be classified based on their
effect on the mechanical properties of results mixture.
Generally, filler was used to fill the gaps for the surface of material. There were
several types of fillers that used in industries. For example wood filler, reinforcing filler,
extender, inert filler, hardener and etc.
2.5.1 INDUSTRIAL FLOUR
Industrial flour also known as Wood Flour. Wood flour was a finely ground product
manufactured from the waste stream of lumber using industries and the protein contains
was about 12%. Wood flour had a variety of uses based upon physical or chemical
characteristics. Applications can be as simple as being a soil extender in a nursery much to
open the soil or as complex as becoming a filler in a plastic resin matrix imparting unique
properties (American Wood Fibers, 2011).
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2.5.2 PALM KERNEL CAKE
Currently Malaysia produced annually quantity of 1.4 million tons of palm kernel
cake (PKC) as a by-product in the milling of palm kernel oil. PKC was considered a
medium grade protein feed, which containing 14.6 to16.0% crude protein, useful for
fattening cattle either as a single feed, with only minerals and vitamins supplementation, or
mixed with other feedstuffs. It had also become the main ingredient in dairy cattle ration.
Two types of PKC exist, the expeller pressed and the solvent extracted, because of different
methods of kernel oil extraction and differences in their oil content; 5 to 12% in the
expeller pressed PKC and 0.5 to 3% in the solvent extracted type. Although PKC supplied
both protein and energy, it was looked upon more as a source of protein. PKC by itself was
a medium grade protein feed and with its high fiber content it was often consider as suitable
for feeding of animals. PKC was ranked a little higher than copra cake but lower than fish
meal and groundnut cake especially in its protein value (Devendra et.al, 1977). A.Bono
et.al (2010) stated that the palm was pre treatment of palm kernel because it was obtained
from the Palm Oil Mill that contained of trace oil.
2.5.3 PALM KERNEL MEAL
The global production of PKM was increased due to the tremendous growth of the
oil palm industry in many parts of Asia and Africa. Malaysia currently produced 2460
Metric Tone of Palm Kernel Meal, the current global leader in the oil palm industry
(PORLA 2000). Palm Kernel Meal was by product from the manufacturing of palm kernel
oil by using the mechanical extraction of palm kernels process. Dark brown protein meal
contained high relative oil and high fiber levels. Palm kernel meal was a good source of
protein and fat. However the protein level in the Palm Kernel Meal which 20 % will help to
reduce the formaldehyde emission.
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However, the Palm Kernel Meal was the post treatment of palm kernel which from
palm kernel cake (PKC) by using soxhlet solid-liquid extraction technique in order to
remove prior oil. The traced oil must to remove to avoid interference during the production
of wood adhesive. Prior the palm kernel cake was grinded to form the fine particle to
improve the extraction efficiency. The extraction was done at solvent boiling point which is
Iso-Propanol and was left running for 10h and then dried in oven for removal of trace
solvent (A.Bono et.al,2010).
2.5.4 SOY BEAN MEAL
According to Evangelista (2010), the improvement of reforming capability based on
the modification of the formulations by increasing the quantities of soy flour. All the
modified glues containing soy flour or concentrate had good reforming properties and
adhesive strengths that were at least equal to that of the control glue. Simple cost analysis
also indicated that when soy flour was used, the modified formulations were cheaper to
produce than the current blood-based glue. Soybean meal, as received, contained very little
oil (0.9%db) and 52.8% (db) crude protein. The amount of oil determined was close to the
typical 0.6% (db) in commercial soybean meal and the protein content was, likewise,
within the 49–54% (db) reported for the meal (Wolf WJ, 1983).
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Table 2.2: Viscosities and Bonding Strength of Plywood With IF and Soybean Meal
(Evangelista, 2010)
Parameters Protein Extenders
IF
(13.8%CP,db)
Soybean Meal
(52.8%CP,db)
Soybean Meal
Modified
Glue viscosity after
mixing,CP
2345±205a 1010±85b 1145±265b
Glue viscosity after
overnight standing,CP
2330±170a 1275±95b 1080±305c
Wet tensile strength,psi 211±42a 186±36b 209±44a
*Values are mean ±standard of duplicate preparation of glue mixes for viscosity and six
boards(20 test specimens per board) in total from duplicate glue mixes for tensile strength.
Values across columns followed by different letters are significantly different (p>0.05) CP
crude protein,db dry basis
Based on above, ground soybean protein products will wet and swell in water, but
remain undispersed until treatment with strong alkali (Lambuth AL, 1994). However,
Lambuth (1994) aslo reported that the akaline process releases useful adhesive properties of
the meal by breaking the internal hydrogen bonds of the ussualy coiled protein molecule,
unfolding the structure and making the exposed reactive group from amino acids available
for wood adhesive. Babcock GE et.al, (1947) have been used the soybean meal in the
Phenolic Resins formulation as wood adhesive for lab to find the strength specifications
and also to shows the favorable resistant to mold action and exterior weathering conditions.
Although the soybean was modified to incrased the performance but it still the lower one.
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2.5.5 BARK STEM
The incorporation of bark along with wood in particleboards has also been studied.
Generally, as bark usage increases, particleboard strength decreases (Muszynski et.al.,
1984, Blanchet et.al, 2000). In order to increase the performance, desirable filler features
include low cost, consistent quality, and sufficient supplies commonly used in wood
adhesive production. Seller (1994) stated that, a few report described the used of bark in
made wood adhesive mixed fillers.
According to Eberhardt et.al, (2006), the bark stem based filler was prepared from
the bark meal. The bark filler fractions passing through 200, 35 and 80-mesh sieves by
sieve shaker after blending processing. The preparation of adhesive was prepared as in table
2.3 using the three bark-based fillers and a furfural residue control (FuraTex, Bates & Co.,
Inc.).
Table 2.3: Adhesive mix for bonding plywood (Eberhardt et.al, 2006)
COMPONENT ADHESIVE MIX (%) MIX SOLID (%)
Filler 6.7 15.0
Extender 7.4 16.6
Sodium Hydroxide solid 1.6 3.6
Resins solid 28.9 64.8
Total mix solid 44.6 100.0
Total mix water 55.4
Total mix 100.0
Values for percent wood failure and shear strength are shown in Table 2.4 by using
four different times to assess the performance of bark-based fillers.
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Table 2.4: Wood Failure and Shear Strength Performance for Bark-based Fillers
(Eberhardt et.al, 2006).
TEST FILLERS
TYPE
ASSEMBLY TIME (MIN)
10 20 40 60
Wood
Failure (%)
Bark filler A 45 66 61 73
Bark filler B 90 91 91 91
Bark filler C 80 86 88 93
Furfural Residue 57 77 92 77
Shear
Strength
(KPa)
Bark filler A 1510 1440 1470 1270
Bark filler B 1610 1740 1450 1630
Bark filler C 1790 1570 1490 1460
Furfural Residue 1690 1500 1480 1520
** Bark-based fillers were prepared from bark fractions rich in eitherobliterated phloem
(filler A) or periderm (filler B) tissues; a fillerwas also prepared from whole bark (filler C)
as received.
Despite the problems encountered with bark filler A, the values for shear strength
were not indicative of poor performance while the ash content of bark filler B was
considerably lower than that obtained for bark filler. Thus, through the grinding and
classification processes employed, plywood adhesive mix filler with improved performance
and lower ash than that which could be obtained by directly grinding the bark as received
was able to produced. Moreover, under the conditions employed, a filler based on bark can
be produced that can perform as well as furfural residue. The working performance of bark
filler increased according to the layer of the bark. The internal layer of bark stem had the
good performance compared to external bark stem (Eberhardt et.al, 2006).
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2.6 USING OF FILLER (C.A.Harper, 2002)
The using of fillers was depends on their types.
Reinforcing filler
Reinforcing filler was used to improve certain mechanical properties such as
modulus or tensile strength. Besides, it also used to increase the tensile,
compressive and shear strength, increased the heat deflection temperature, reduced
the shrinkage, and improved the modulus and creep behavior.
Extender
Using of extender was to reduce the cost of compound.
Inert filler
Inert filler was use in industries to increase the density of compound, reduce the
temperature, improve the hardness and increase the heat deflection temperature.
Basically, the filler in the wood adhesive was used to fill up all small holes at the
surface of wood to prevent or to reduce the formation of weaker boding. Besides that,
fillers also used to reduce the penetration of resin into the small holes of the wood (A.Pizzi
et.al, 1994). Harper (2002) stated that the filler was used in term to promote interaction
with the polymer and allowed for good interfacial adhesion and also made the good
interfacial bonding. According to Ebnesajjad et.al (2008), filler was used to reduce the
material cost. It also used to modify adhesives to manage such properties. For example heat
resistance, thermal conductivity and thermal expansion.
CHAPTER 3
METHODOLOGY
3.1 MATERIALS
The materials that used in this research were Melamine Urea Formaldehyde (MUF)
resins as a raw material of wood adhesives. In order to produce the adhesive, the
formulations of MUF resins were used were mixed with the filler and hardener. For fillers,
the materials used were pre treatment palm kernel which was Palm Kernel Cake (PKC) and
post treatment palm kernel was Palm Kernel Meal (PKM) and also industrial flour (IF).
Below show the chemical that will be used during experiment progress.
1. 37% Formalin
2. Urea
3. Melamine
4. Ammonium Chloride
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3.2 APPARATUS
In this research, below show the apparatus that will be used during experiment
progress.
a. Viscometer g. Sieve Shaker Machine
b. Heating Mantel h. Motor Mixer
c. Universal Testing i. Water Bath
d. Indicator Paper j. Thermometer
e. Four-Necked Flask
3.3 EXPERIMENTAL WORKS
Figure 3.1: Flow chart of the research method
collection for literature review
preparation of palm kernel, meal palm kernel cake and industrial flour in diferrent size as a fillers. Sieve shaker experimet will be done get the uniform sizes of fillers's
particle size.
preparation of melamine-urea formaldehyde (MUF) resin [3]
wood adhesive production
performance test of wood adhesive based on 3 factors such as Temperature 0C , Pressing time s, and materials
Shear strength test
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3.4 PREPARATION OF MUF RESIN (Awang Bono et.al, 2003)
Formalin (37%) was poured into the four-necked flask followed by melamine and
first urea. The mixture was blended homogenously using a stirrer connected to a motor
(VELP Scientifica stirrer), which was set to speed 50 rpm. The mixture has a white colored
solution. Then, pH was adjusted to a range of 8.8 to 9.0 by adding few drops of
NaOH/caustic soda solution (20%) or soda ash solution (25%). At the same time, solution
pH and temperature were recorded. The temperature and pH was recorded for every 5
minutes till the end of the production process. After that, heating process was started and at
the same time, stopwatch was started until the temperature reached 80˚C. This temperature
was maintained until end point was reached. The temperature maintained was subjected to
change according to desired temperature which could be 80˚C, 85˚C or 90˚C. The end point
can be determined by dropping the mixture solution into a beaker of water at 30˚C
temperature for every 5-10 minutes. If the droplet is diluted in the water, without any trace
(no whitish streak), meaning the end point has not achieved yet. Next, the condition of the
solution was observed during this period. The initial white solution would turn clear at the
temperature between 70˚C-80˚C. When the end point was reached, the heating process was
stopped while continued stirring. NaOH/caustic soda solution (20%) or soda ash solution
(25%) was added slowly to increase the pH value to a range of 8.8 to 9.5 this is in order to
stop the polymerization of resin. The solution was allowed to cool down to ambient
temperature by immersing the four-necked flask into cool water. Second urea was added
when the temperature dropped to 60˚C. The cooled resin was transferred to a plastic
container for further testing and plywood production.
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Figure 3.2: Schematic Equipment Set Up for Resin Production (Bono.A, 2003)
3.5 PREPARATION OF GLUE
300g of MUF Resin was weighted into beaker. Then, 12 g of Urea was added into
the MUF resin mixed well with a mixer for 5 minutes. After that, this was followed by 50g
of filler and mixed well for 5 minutes. Next, the 13 g of hardener which is ammonium
chloride was added into the mixture and mixed for 5 minutes. The initial viscosity of the
glue prepared should be 20 until 24 cps. If the glue viscosity below this range, it could be
adjusted with filler. Glue pot life was checked and recorded for every 30 minutes until it
exceed 150 cps by using viscometer, with first spindle. However these, glue only exceed
for 9 samples. The ratios of each type of elements for the glue preparation are:
1) MUF resin = 80%
2) Urea = 3.2%
3) Filler = 13.33%
4) Hardener = 3.47%
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3.6 SAMPLE PLYWOOD MAKING
Core was put on the analytical balance and the reading was set to zero. 21 g of wood
adhesive or glue was poured on one of the core surface and the glue was spread on it by
using glue spreader. The face veneer was put on the core surface and clamped together. The
face veneer grain direction should opposite with the core grain direction. This step was
repeated by applied it for another side of the core and back veneer. Then, this plywood was
undergo cold press process for 20 minutes with pressure 9 kg/cm2
and followed by hot
press with pressure 9kg/ cm2
and temperature 125±5˚C for 224 seconds. The preparation of
the testing normal samples using hot press at pressure 1MPa is as given in table 3.1.
Table 3.1: samples preparation for hot press
TEMPERATURE
(0C)
PRESSING TIME
(s) SAMPLE
100
50 P1
150 P2
250 P3
125
50 S1
150 S2
250 S3
150
50 T1
150 T2
250 T3
22
3.7 PERFORMANCE TEST OF WOOD ADHESIVE (Awang Bono et.al,2003 and
JAS,2003)
3.7.1 PLYWOOD TESTING METHOD
3.7.1.1 SHEAR STRENGTH TEST
1. Preparation of test pieces
9 to 12 test pieces with a dimension shown below shall be prepared from each sample of
plywood.
Figure 3.3: Plywood Test Pieces
2. Cyclic Boiling Test
Test pieces, after being immersed in boiling water for 4 hours, are dried at a temperature of
60±30C for 20 hours. Further the test pieces are immersed in boiling water for 4 hours, and
immersed in water of room temperature to get cool. After that, bonding strength test shall
be conducted in a wet condition, and measure the maximum load and wood failure ratio
and then calculate the shear strength and average wood failure ratio. The shear strength was
done by using the Universal Testing Machine (UTM).
23
3.8 EXPERIMENTAL DESIGN ANALYSIS
For the analysis, the three level factorial of Response Methodology Surface (RSM)
Design Expert (version 6.0.8, Stat-Ease Inc., Minneapolis, USA) was chosen in doing the
analysis for predicted the value of the shear strength of each samples. Constrains were
constructed as in table 3.2.
Table 3.2: RSM Analysis Construct
PARAMETER UNIT LOWER
LIMT
UPPER
LIMIT
A: Temperature Degree C
(0C)
100 150
B: Pressing Time Second (s) 150 250